Date: Sun, 21 Nov 2010 14:35:32 +0100 From: Jilles Tjoelker <jilles@stack.nl> To: Gavin Atkinson <gavin@FreeBSD.org> Cc: svn-src-stable@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, svn-src-stable-8@freebsd.org Subject: Re: svn commit: r215572 - stable/8/sys/sys Message-ID: <20101121133531.GB17293@stack.nl> In-Reply-To: <alpine.LNX.2.00.1011211241060.2142@ury.york.ac.uk> References: <201011201646.oAKGkGW7019085@svn.freebsd.org> <alpine.LNX.2.00.1011211241060.2142@ury.york.ac.uk>
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On Sun, Nov 21, 2010 at 12:42:24PM +0000, Gavin Atkinson wrote: > On Sat, 20 Nov 2010, Jilles Tjoelker wrote: > > Author: jilles > > Date: Sat Nov 20 16:46:16 2010 > > New Revision: 215572 > > URL: http://svn.freebsd.org/changeset/base/215572 > > Log: > > MFC r215183: Make POLL_ERR and POLL_HUP different. > > The kernel currently does not generate any of the POLL_* constants, but > > some applications use them and break if they are not all distinct. > Is this a good idea to merge to a stable branch? Presumably some of those > same applications will now break due to the constants changing? The typical usage appears to be switch (si->si_code) { case POLL_IN: ...; break; ... case POLL_ERR: ...; break; case POLL_HUP: ...; break; } This doesn't compile if some of the constants are equal. Boost has worked around FreeBSD's weirdness by placing a #if defined(POLL_ERR) && defined(POLL_HUP) && (POLL_ERR - POLL_HUP) around the case POLL_HUP. This #if does not hurt systems that have the POLL_* values all distinct. Given that the kernel does not generate these anyway, I considered this safe enough. True SIGIO, which is similar to SIGPOLL, always puts si_code=SI_KERNEL. -- Jilles Tjoelker
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